0003839: Trigger capture with fallback to slower

use_capture_lob/contains_big_lob (Oracle)

symmetric-assemble/src/asciidoc/configuration/table-triggers.ad

@@ -72,12 +72,12 @@ Custom Insert Trigger Text:: Specify insert trigger text (SQL) to execute after
 Custom Update Trigger Text:: Specify update trigger text (SQL) to execute after the SymmetricDS trigger fires.  This field is not applicable for H2, HSQLDB 1.x or Apache Derby.
 Custom Delete Trigger Text:: Specify delete trigger text (SQL) to execute after the SymmetricDS trigger fires.  This field is not applicable for H2, HSQLDB 1.x or Apache Derby.
 Sync On Incoming:: Whether or not an incoming batch that loads data into this table should cause the triggers to capture data_events. Be careful turning this on, because an update loop is possible.
-Stream Lobs:: Specifies whether to capture lob data as the trigger is firing or to stream lob columns from the source tables using callbacks during extraction. A value of 1 indicates 
-to stream from the source via callback; a value of 0, lob data is captured by the trigger.
-Capture Lobs:: Provides a hint as to whether this trigger will capture big lobs data.  If set to 1 every effort will be made during data capture in trigger and during data selection for 
-initial load to use lob facilities to extract and store data in the database.  On Oracle, this may need to be set to 1 to get around 4k concatenation errors during data capture and during initial load.
-Capture Old Data:: Indicates whether this trigger should capture and send the old data (previous state of the row before the change).
-Stream Row:: Captures only the primary key when the trigger fires which can reduce the overhead of the trigger on tables with lots of columns.  The data will then be queried using the PK values captured when the batch is ready for extraction.
+Stream Lobs:: Specifies to capture an empty placeholder for LOB data types when a row is changed, then query for the LOB value later when the batch is extracted.
+It usually performs better to leave this disabled, which means it will capture LOB data types when a row is changed.
+Capture Lobs:: Provides a hint that the table may have row data that is wider than the character limit imposed by the database, requiring the trigger to capture changes as a LOB type.
+Capture Old Data:: Indicates whether this trigger should capture and send the old data, which is the previous state of the row before the change.
+Enable this option if you need to access old data in custom trigger text, routing expression, or transform expression.  Otherwise, disable this option for better performance. 
+Stream Row:: Captures only the primary key when the trigger fires, which can reduce overhead for tables with wide data or many columns.  The data will be queried using the PK values when the batch is extracted.
 External Select:: Specify a SQL select statement that returns a single row, single column result.  
 It will be used in the generated database trigger to populate the EXTERNAL_DATA field on the data table.  See 
 Excluded Column Names:: Specify a comma-delimited list of columns that should not be synchronized from this table.